The reason we don't recognize creativity in our daily lives is that we don't always 'feel' creative when we're going about them. Many people treat their creative selves like the good china; they only consciously bring it out for special occasions. Eventually, no occasion is good enough and what once was a creative pursuit becomes boring and routine. People become stagnant, doing the same thing over and over. Stagnation isn't healthy for any living thing and mental stagnation often signals the beginnings of a decline in physical health.
How, then, can we ward off stagnation? I would suggest, and there are multiple authors who agree, that a person can deliberately court the muse. Doing something occasionally that inspires you to be creative, no matter what form that creativity takes, keeps your mind limber. There is a growing body of research on the way music and painting affect people who are suffering from Alzheimer's. People who participated actively in these forms of creativity did not decline as rapidly as those who did not.
So, find something that inspires you to be creative and go do it. Sing because you want to. Paint because you feel like it. Do it alone, for yourself, if you don't want anybody to see. Don't make an excuse. If you don't think you're any good, remember that you can only get better through practice.